Revision notes 10: Pharmacology Flashcards
3 drugs that don’t cross placenta
Heparin
Insulin
Tubocurarine
Drugs that cause abortion
MET
Misoprostol
Ergotamine
Thrombolytic
Domperidone moa
dopamine antagonist
stimulates milk production
Drugs interfering with folate metabolism
Sulfonamide - inhibits conversion of benzoic acid to folate
Dihydrofolate reductase inhibitors
Trimethoprim
Methotrexate
Pyrimethamine
Aciclovir is an analogue of
guanine
it inhibits viral dna polymerase
Promethazine is an antagonist of what
H1 histamine antagonist
Ranitidine is an antagonist of what
H2 receptor antagonist
When are glucocorticoids given for fetal lung maturity
24h to 7 days before pre-term delivery
Up to 34+6 gestation
35+6 if SGA
finasteride mechanism of action
5a reductase inhibitor
prevents conversion of testosterone to dihydrotestosterone
Mifepristone
Binds to progesterone receptor but transcription inhibited
I.E anti-progestogenic
Mifepristone abortion rate on its own
60-80% effective
Contraindications to misoprostol
Suspected ectopic pregnancy Chronic adrenel insufficiency Long-term corticosteroid therapy Haemorrhagic disorders Anti-coagulant therapy Smokers over the age of 35 (avoid smoking / alcohol 2 days before and on the day of prostaglandin administration) Hepatic / renal impairement Avoid aspirin / NSAIDS for at least 8-12 days after mifepristone.
Ulipristal acetate (30 mg)
Contraceptive use?
Up to 5 days after intercourse
Selective progesterone receptor modulator
Once per cycle. If continuing with hormonal contraception, should use condoms until next period or withdrawal bleed
Absolute contraindications to COCP
Smoker >15/day over 35 yrs old <6 weeks post-partum hypertension 160/100 History of VTE IHD CVA Valvular heart disease Migraine with focal neuro Current breast cancer Diabetes with retinopathy Cirrhosis
Clomiphene - when used
Non-steroidal antioestrogen with weak oestrogenic effects
Days 2-6 of cycle for ovulation induction
Used mainly in PCOS
Causes increase in GnRH, FSH, LH
Tamoxifen oestrogenic effects
Anti-oestrogen in breast
Anti-oestrogen on pre-menopausal uterus
Oestrogenic effects on post-menopausal uterus (inc risk endometrial carcinoma/hyperplasia
Bromocriptine & cabergoline & quinagolide
Dopamine agonists
Used to inhibit pituitary prolactin
Quinagolide - non-ergot pituitary selective dopamine-2 receptor agonist used when bromo dont work
PGE2 otherwise known as
Dinoprostone
Induction of labour
aspirin moa
IRREVERSIBLE inactivation of COX enzyme required for prostaglandin + thromboxane synthesis
furosemide site of action
ascending loop of henle
Aromatase inhibitors - two types
Irreversible - exemestane
Non-steroidal inhibitors - reversible
- Anastrozole, letrozole
Labetolol mechanism
Selective competitive alpha 1 adrenergic blocker
non-selective competitive beta adrenergic blocker
dose-related fall in BP without reflex tachy and without significant reduction in heart rate
Hydralazine moa
Vascular smooth muscle relaxation, decreased PVR
Causes reflex tachy + inc cardiac output
Can cause a syndrome similar to Lupus
idarucizumab is antidote for what
Dabigatran
Alkylating agent moa
Form covalent bonds with DNA side chains, causing depurination, strand breaks and cross-linking.
This drug decomposes within cells to form phosphoramine mustard and acrolein
Cyclophosphamide
Paclitaxel mechanism
Binds to micro-tubules to disrupt mitosis
First line treatment choriocarcinoma
methotrexate
methotrexate mechanism
inhibits dihydrofolate reductase
azathioprine is converted to which active forms
6-mercaptopurine
6-thioinosinic acid
This chemo drug binds to tubulin preventing polymerisation and disrupting mitosis
Vincristine/vinblastine
warfarin works by
inhibiting vit k epoxide reductase (recycles oxidised vitk to its reduced form
warfarin metabolism
hepatic microsomal mixed function oxidases
Why is aspirin contraindicated in neonates and children
risk of rye syndrome
MFO inducers
Carbamazepine Ethanol Groseofulvin Phenobarbitone Phenytoin Rifampicin
They INCREASE metabolism of glucocorticoids, contraceptives, theophylline, warfarin - need higher dose
Inhibitors of hepatic enzymes
1) Phenelzine
2) Cimetidine
3) Isoniazide
4) Sodium valproate
5) Sulphonamides
6) Erythromycin
7) Theophylline
safest ssri during pregnancy
fluoxetine
SSRI taken after 20 weeks - risk of
persistent pulmonary hypertension
when does the neural tube close?
day 28
clozapine risk to fetus
agranulocytosis
folic acid dose if on valproate
5mg/day
lithium risks to fetus
increase risk of fetal heart defects: 60-1000 from 8-1000
Inc risk Ebstein’s anomaly - 1 in 20,000 to 10 in 20,000
Lamotrigine in breast feeding women - significance
avoid
can cause Stevens-Johnson syndrome in the infant
methotrexate - toxicity increased by:
antifolates e.g. trimethoprim, pyimethamine
sulphonamides
penicillin
probenecid
Suxamethonium is a
nicotinic agonist
tubocurarine, pancuronium, atracurium are examples of
competitive nicotinic antagonists
Examples of muscarinic antagonists
Atropine Hyoscine Ipratropium bromide Imipramine Quinidine
All competitive antagonists
examples of competitive cholinesterase inhibitors
neostigmine
Physostigmine
Doxazosin mechanism of action
alpha-adrenergic antagonist that inhibits a1 receptors
Anti-hypertensive
High affinity for alpha-1c adrenoceptor –> used in BPH
benzo antagonist
flumazenil
Anti-cholinergics for detrusor overactivity
oxybutynin, tolterodine
mirabegron mechanism
b3-receptor agonist
Detrusor relaxation
Treat OAB
First-line tocolytic
if contraindicated?
Nifedipine - calcium channel antagonist
Atosiban if contra (competitive oxytocin receptor antagonist)
maximum contraction rate when using oxytocin for induction of labour
no more than 4-5 every 10 minutes
Treatment of uterine hyperstimulation
terbutaline
what is carboprost
PGF2a analogue (synthetic prostaglandin)
what is misoprostol
synthetic prostaglandin E1 analogue
misoprostol important side effects
Severe diarrhoea requiring withdrawal
associated with magnesium containing antacids
medical treatment of stress urinary incontinence
duloxetine
Why is nitrofurantoin avoided at term
risk of neonatal haemolysis
plasma half life of oxytocin
1-6 minutes
Following IV admin of oxytocin, effects subside within
1 hour
embryopathic effect of warfarin occurs when
6-9 weeks
firstline suppression of lactation
cabergoline
properties of acidic drugs
higher oral bioavailability
poorer hepatic clearance
higher protein binding
smaller volumes of distribution
anti-epileptic that increases risk of pcos
valproate
uti drug in late pregnancy
trimethoprim
indomethacin mechanism of action
cycloxygenase inhibitor
molecular structure of heparin
polysaccharide
main adrenergic receptor mediating detrusor relaxation
beta 3
adrenergic receptors present in urinary bladder
beta 1, beta 2, beta 3
Drug class that increases haematological toxicity of methotrexate
corticosteroids
